A vacuum cleaner is an electrically powered, mechanical appliance utilized for the dry removal of dust and loose dirt from carpets, rugs, fabrics, bare floors and other surfaces. Vacuum cleaners have been widely utilized for years in domestic and industrial cleaning applications.
In operation, a pressure drop is utilized to force air entrained with loose dirt and dust into the nozzle of a vacuum cleaner. The dust and dirt laden air is then drawn through a bag which traps and retains the dirt. The air is then exhausted by electric fan through an additional filter to remove relatively fine particles. It is this fan that provides the air pressure drop or vacuum that provides the cleaning action.
It is only possible to maximize free airflow and thus cleaning ability by employing uniform airflow through the entire available surface area of the filter bag: that is the area above the level of accumulated dirt and debris. However, an inherent problem in the design of current bag vacuum cleaners prevents the filter bag from maximizing its full volume and, accordingly, air power (i.e. suction and air velocity) drops off rapidly with material ingestion. Specifically two primary functional flaws combine to decrease cleaning efficiency.
First, the filter bag in prior art vacuum cleaners expands with airflow to contact the surrounding vacuum or bag chamber walls. As a consequence, no air gap or passage is maintained between the filter bag and the inner chamber wall surface. This functions to seal off airflow through the entire circumferential surface area of the filter bag. With no alternative pathway available, air is then forced to flow entirely through the bottom of the bag and any accumulated material therein. This decreases the total airflow and the motor efficiency.
Second, the vacuum chamber outlet or plenum mouth is typically undersized, requiring a sharp bend in the flow path from the outer periphery of the bag bottom resulting in increased flow resistance and back pressure. When considered together these two problems have a very significant adverse effect on the cleaning efficiency of the vacuum cleaner as the filter bag is filled with material.
U.S. patent application Ser. No. 11/191,736, filed 28 Jul. 2005 and owned by the assignee of the present invention addresses and resolves both of these problems. The vacuum cleaner disclosed in that document incorporates a bag cage that advantageously affords prolonged air power with progressive ingestion of material thus maximizing the capacity of the filter bag and the cleanability of the vacuum cleaner. The present invention relates to an improvement of that basic design. Specifically, the bag cage of the present invention incorporates a bag caddy that allows the operator to more conveniently change the filter bag.